1. Open Eudora.
2. Click the "Tools" menu and select "Options".
3. Select "Getting Started".
4. In the "Real name" text box, enter the name you want displayed on your emails.
5. In the "Return address" field, enter your email address (i.e. jsmith@yourdomain.com).
6. In the "Mail Server (Incoming)" field, enter "mail" and your domain name (i.e. mail.yourdomain.com).
7. In the "Login Name" field, enter the username you gave when setting up your email account.
8. In the "SMTP Server (Outgoing)" field enter "mail" and your domain name (i.e. mail.yourdomain.com).
9. Check the "Allow Authentication" box.
10. Click "OK."

If you've configured everything correctly, you should be able to "send and receive" with no errors.